Absorbent articles having an aliphatic-aromatic copolyester film

ABSTRACT

An absorbent article comprising a laminated outer cover is disclosed. The laminated outer cover comprises an aliphatic-aromatic copolyester film including a filler material. The aliphatic-aromatic copolyester films have suitable breathability, vapor transfer and tensile strength properties while being substantially biodegradable.

BACKGROUND OF THE INVENTION

The present invention is directed to absorbent articles such as diapersthat contain an outer cover that comprises a substantially biodegradablefilm material. More particularly, the present invention is directed toabsorbent articles that contain an outer cover made from a film materialcomprised of an aliphatic-aromatic copolyester material that showsimproved biodegradability after use. When filled with a filler materialsuch as calcium carbonate, the aliphatic-aromatic copolyester filmmaterial has high breathability and good barrier and tensile strengthproperties.

People rely on disposable absorbent articles, such as diapers, to maketheir lives easier. Diapers commercially available today are generallycomfortable to the wearer, and provide a good barrier against leakageout of the diaper. Despite providing good barrier properties againstliquids, many commercially available diapers allow water vapor to passthrough the diaper and into the environment to lessen the amount ofmoisture held against the skin and reduce the chance of skin irritationand rash due to skin overhydration. In order to allow the passage ofvapor through the diaper and into the environment while holding liquid,many diapers comprise a laminated outer cover, often referred to as abreathable outer cover.

Generally, this breathable outer cover is comprised of a non-wovenouter-facing layer joined to an inner-facing linear low densitypolyethylene layer. The polyethylene layer will typically comprisecalcium carbonate, which causes a series of openings to develop in thepolyethylene layer when the film is stretched prior to use in theproduct, which ultimately allows water vapor to pass through withoutallowing liquid to pass through.

Although most commercially available diapers today comprise an outercover suitable for achieving the goals outlined above, one shortcomingto date has been that the polyethylene used in the manufacturing of thediaper, and specifically one layer of the outer cover, is notsubstantially biodegradable. Because of the popularity of diapers andother absorbent products and the large number of these products that areutilized each year, it could be beneficial to provide absorbent articlecomponents that exhibit improved biodegradability in landfills after useand disposal.

SUMMARY OF THE INVENTION

The present invention is directed to absorbent articles or productscomprising a film with improved biodegradable properties. The film,which is particularly useful as one component of an outer cover of anabsorbent article, is comprised of an aliphatic-aromatic copolyester.The film also comprises calcium carbonate or other suitable fillermaterials such that, upon stretching, pores develop around the fillermaterial. These pores allow for the passage of water vapor but not thepassage of liquid. The film also possesses high breathability and goodbarrier and tensile strength properties.

In one embodiment, the film comprises filler particles and a copolyesterthat comprises three monomers: 1,4-butanediol, terephthalic acid, andadipic acid. The copolyester has a weight average molecular weight offrom about 90,000 to about 160,000 Daltons and a number averagemolecular weight of from about 35,000 to about 70,000 Daltons, andcomprises a total of 40 mole % to about 60 mole % of acid comonomers.

Therefore, the present invention is directed to an absorbent articlecomprising a laminated outer cover. The laminated outer cover comprisesa biodegradable stretched aliphatic-aromatic copolyester film. The filmcomprises filler particles and a copolyester comprising from about 10mole % to about 30 mole % of aromatic dicarboxylic acid or esterthereof, from about 20 mole % to about 40 mole % of aliphaticdicarboxylic acid or ester thereof, and from about 30 mole % to about 60mole % dihydric alcohol. The weight average molecular weight of thecopolyester is from about 90,000 to about 160,000 Daltons and the numberaverage molecular weight of the copolyester is from about 35,000 toabout 70,000 Daltons. The glass transition temperature of thecopolyester is less than about 0° C.

The present invention is further directed to an absorbent articlecomprising a laminated outer cover. The laminated outer cover comprisesa biodegradable stretched aliphatic-aromatic copolyester film. The filmcomprises filler particles and a copolyester comprising from about 10mole % to about 30 mole % terephthalic acid, from about 20 mole % toabout 40 mole % adipic acid, and from about 30 mole % to about 60 mole %1,4-butanediol. The copolyester has a weight average molecular weight offrom about 90,000 to about 160,000 Daltons and a number averagemolecular weight of from about 35,000 to about 70,000 Daltons. The glasstransition temperature of the copolyester is less that about 0° C.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plot of the geometric mean of the machine direction andcross direction strain at break data against the calcium carbonatefiller level of various films.

FIG. 2 is a plot of the geometric mean of the machine direction andcross direction modulus data against the calcium carbonate filler levelof various films.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

The present invention is generally directed to disposable absorbentproducts which comprise an aliphatic-aromatic copolyester film. Thealiphatic-aromatic copolyester film, which in one embodiment may beutilized in combination with a spunbonded nonwoven material to form acomposite outer cover, also comprises a filler material which impartsseveral desirable characteristics including high breathability and goodbarrier and tensile strength properties. Additionally, thealiphatic-aromatic copolyester films as described have improvedbiodegradable properties as compared to conventional film materials suchas linear low density polyethylene.

Although described primarily herein in connection with a composite outercover of an absorbent product, such as a diaper, it will be recognizedby one skilled in the art based on the disclosure herein that thealiphatic-aromatic copolyester films described herein may be utilized inother areas of an absorbent article in addition to the outer cover. Forexample, fecal containment members, such as those described in U.S. Pat.No. 5,676,661 (Faulks et al.) may comprise the copolyester filmsdescribed herein.

Additionally, although described primarily herein in connection with adiaper, it will be recognized by one skilled in the art based on thedisclosure herein that the aliphatic-aromatic copolyester filmsdescribed herein could also be used in a variety of other absorbentarticles including, but not limited to, training pants and adultincontinence garments. Also, the aliphatic-aromatic copolyester filmsdescribed herein could also be used in connection with non-absorbentarticles. Suitable non-absorbent articles include, for example, surgicaldrapes, surgical gowns, and the like.

As used herein, the term “precursor film” is meant to include films thathave not been stretched prior to use and/or evaluation and analysis.This includes films that contain a filler material, such as calciumcarbonate, that have not been stretched to create the pores around thecalcium carbonate to allow water vapor to pass through the film.

As used herein, the term “stretched film” is meant to include films thathave been stretched to create pores around a filler material. Thesestretched films are ready for use in an absorbent article as they willallow water vapor to pass therethrough.

As used herein, the term “biodegradable” or “biodegradable polymer”refers to a polymer that can be readily decomposed by biological means,such as a bacterial action, environmental heat and/or moisture. Whentested according to ASTM D6340-98, a biodegradable polymer is one thatis at least about 80% dissolved and/or decomposed (oxidized) after 180days in a controlled compost environment as set forth in the procedure.

Typically, the outer cover of a diaper is a multi-layered laminate orcomposite structure, such as a necked, multi-layer laminate structure.Such a laminated composite structure provides the desired levels ofextensibility as well as liquid impermeability and vapor permeability.The laminated structure typically comprises an outward-facing layer andan inward, or bodyfacing-layer. The outward-facing layer is generallyconstructed of a vapor and liquid permeable non-woven material, and theinward-facing layer is generally constructed of a liquid impermeable,vapor permeable material. Such a combination allows for the transmissionof vapor through the diaper and into the environment along with theholding of liquid in the diaper. The two layers are generally securedtogether thermally or by a suitable laminating adhesive. Thermal bondingincludes continuous or discontinuous bonding using a heated roll. Pointbonding is an example of such a technique. Thermal bonds should also beunderstood to include various ultrasonic, microwave, and other bondingmethods wherein the heat is generated in the non-woven or the film.

The liquid permeable outward-facing layer can be any suitable materialand is desirably one which provides a generally cloth-like texture.Suitable neckable materials for the outward-facing layer includenon-woven webs, woven materials and knitted materials such as thosedescribed in U.S. Pat. No. 4,965,122 (Morman). Non-woven fabrics or webshave been formed from many processes, for example, spunbondingprocesses, bonded carded web processes, meltblowing processes andspunbonding spunlacing processes. Morman describes stretching amaterial, such as a non-woven, in one direction such that the materialreversibly narrows or “necks” in the perpendicular direction. Thenon-elastic neckable material is desirably formed from at least onemember selected from fibers and filaments of inelastic polymers. Suchpolymers include polyesters, for example, polylactic acid, polyhydroxyalkanoate, polyethylene terephthalate, polyolefins, for example,polyethylene and polypropylene, and polyamides, for example, nylon 6 andnylon 66. A preferred material is a spunbond polypropylene. These fibersor filaments are used alone or in a mixture of two or more thereof.Suitable fibers for forming the neckable material include natural andsynthetic fibers as well as bicomponent, multi-component, and shapedpolymer fibers.

Many polyolefins are available for fiber production including, forexample, fiber forming polypropylenes including Exxon Chemical Company'sEscorene PD 3445 polypropylene and Himont Chemical Company's PF-304.Polyethylenes such as Dow Chemical's ASPUN 6811A linear low densitypolyethylene is also a suitable polymer. The nonwoven web layer may bebonded to impart a discrete bond pattern with a prescribed bond surfacearea. If too much bond area is present on the neckable material, it willbreak before it necks. If there is not enough bond area, then theneckable material will pull apart. Typically, the percent bonding arearanges from around 5 percent to around 40 percent of the area of theneckable material.

One particular example of suitable material from which theoutward-facing layer may be constructed is a 0.4 osy (ounce per squareyard) or 14 gsm (grams per square meter) spunbond polypropylenenon-woven web which is neckable in the range of from about 35% to about45%. Typically, a suitable nonwoven material has a basis weight of lessthan about 30 gsm. Also, while it is not a necessity for theoutward-facing layer of the outer cover to be liquid permeable, it isdesired that it have a cloth-like texture.

Another example of a suitable material from which the outward facinglayer may be constructed is a polylactic acid spunbond, such as thatmanufactured by Unitika (Osaka Japan) or Kanebo (Tokyo, Japan).

The liquid impermeable, vapor permeable inward-facing layer is desirablyconstructed of a stretched aliphatic-aromatic copolyester-containingfilm as described herein. The aliphatic-aromatic copolyester films ofthe present invention comprise: (1) a copolyester that comprises anaromatic dicarboxylic acid or ester thereof, an aliphatic dicarboxylicacid or ester thereof, and a dihydric alcohol; and (2) filler particles.Optionally, a polyfunctional branching agent may also be incorporatedinto the aliphatic-aromatic copolyester films of the present invention.

Methods of preparing polyesters in general and aromatic-aliphaticcopolyesters in particular are known in the art. Most commonly, amixture of monomers, including an aromatic dicarboxylic acid (designatedHOOC—Ar—COOH in the equation below), an aliphatic dicarboxylic acid(designated HOOC—R—COOH in the equation below), and a diol (designatedHO—R′—OH in the equation below) are reacted in the presence of acatalyst. Water is driven off, and under proper conditions, acopolyester results (can be either block or random copolymers), as shownin the following equation:nHOOC—Ar—COOH+mHOOC—R—COOH+(n+m)HO—R′—H→—(OCArCO)_(n)—(OR′O)_(n)—(OCRCO)_(m)—(OR′O)_(m)—+(m+n)H₂O

Alternative synthesis methods include using methyl esters in place ofthe carboxylic acids. In these methods methanol is volatilized ratherthan water during the reaction. Other synthesis methods are also known.

For purposes of this invention, when it is stated that a polyestercomprises various monomers, it assumes that the starting materials werecarboxylic acids and alcohols, as provided in the generalized equationabove. While it is understood that other synthesis schemes may employother types of monomers, reference to copolyesters comprising the statedcarboxylic acids and alcohols is intended to define the finishedpolymer, not the actual starting materials. Also, the precise polymersynthesis method is not critical so long as the desired properties ofthe polymer are achieved.

Any aromatic dicarboxylic acid known in the art can be used as thearomatic dicarboxylic acid monomer of the copolyester of the filmsdescribed herein. Useful aromatic dicarboxylic acids includeunsubstituted and substituted aromatic dicarboxylic acids and the loweralkyl (C₁-C₆) esters of aromatic dicarboxylic acids. Examples of usefuldiacid moieties include those derived from terephthalates,isophthalates, naphthalates, and bibenzoates. Specific examples ofuseful aromatic dicarboxylic acid components include terephthalic acid,dimethyl terephthalate, isophthalic acid, dimethyl isophthalate,2,6-napthalene dicarboxylic acid, dimethyl-2,6-naphthalate,2,7-naphthalenedicarboxylic acid, dimethyl-2,7-naphthalate,3,4′-diphenyl ether dicarboxylic acid, dimethyl-3,4′diphenyl etherdicarboxylate, 4,4′-diphenyl ether dicarboxylic acid,dimethyl-4,4′-diphenyl ether dicarboxylate, 3,4′-diphenyl sulfidedicarboxylic acid, dimethyl-3,4′-diphenyl sulfide dicarboxylate,4,4′-diphenyl sulfide dicarboxylic acid, dimethyl-4,4′-diphenyl sulfidedicarboxylate, 3,4′-diphenyl sulfone dicarboxylic acid,dimethyl-3,4′-diphenyl sulfone dicarboxylate, 4,4′-diphenyl sulfonedicarboxylic acid, dimethyl-4,4′-diphenyl sulfone dicarboxylate,3,4′-benzophenonedicarboxylic acid,dimethyl-3,4′-benzophenonedicarboxylate, 4,4′-benzophenonedicarboxylicacid, dimethyl-4,4′-benzophenonedicarboxylate, 1,4-naphthalenedicarboxylic acid, dimethyl-1,4-naphthalate, 4,4′-methylene bis(benzoicacid), dimethyl-4,4′-methylenebis(benzoate), and the like and mixturesof two or more thereof. Preferably, the aromatic dicarboxylic acidcomponent is derived from terephthalic acid, dimethyl terephthalate,isophthalic acid, dimethyl isophthalate, 2,6-naphthalene dicarboxylicacid, dimethyl-2,6-naphthalate, or mixtures of two or more thereof.Carboxylic acid chlorides or anhydrides of these monomers may also besuitable.

The aromatic dicarboxylic acid is present in the aliphatic-aromaticcopolyester in an amount of from about 10 mole % to about 30 mole %,optionally from about 15 mole % to about 25 mole %, and optionally fromabout 17.5 mole % to about 22.5 mole %.

Any aliphatic dicarboxylic acid known in the art can be used as thealiphatic dicarboxylic acid monomer component of the copolyester thefilms described herein. Useful aliphatic dicarboxylic acid componentsinclude unsubstituted, or substituted, linear, branched, or cyclicaliphatic dicarboxylic acids, and the lower alkyl esters thereof,preferably having 2-36 carbon atoms. Examples of useful aliphaticdicarboxylic acid components include, oxalic acid, dimethyl oxalate,malonic acid, dimethyl malonate, succinic acid, dimethyl succinate,methylsuccinic acid, glutaric acid, dimethyl glutarate, 2-methylglutaricacid, 3-methylglutaric acid, adipic acid, dimethyl adipate,3-methyladipic acid, 2,2,5,5-tetramethylhexanedioic acid, pimelic acid,suberic acid, azelaic acid, dimethyl azelate, sebacic acid,1,11-undecanedicarboxylic acid, 1,10-decanedicarboxylic acid,undecanedioic acid, 1,12-dodecanedicarboxylic acid, hexadecanedioicacid, docosanedioic acid, tetracosanedioic acid, dimer acid,1,4-cyclohexanedicarboxylic acid, dimethyl-1,4-cyclohexanedicarboxylate,1,3-cyclohexanedicarboxylic acid, dimethyl-1,3-cyclohexanedicarboxylate,1,1-cyclohexanediacetic acid, and the like and mixtures of two or morethereof. Carboxylic acid chlorides or anhydrides may also be suitable.Preferred aliphatic acids or esters include succinic acid, dimethylsuccinate, glutaric acid, dimethyl glutarate, adipic acid, dimethyladipate, and dimer acid.

The aliphatic dicarboxylic acid is present in the aliphatic-aromaticcopolyester in an amount of from about 20 mole % to about 40 mole %,optionally from about 25 mole % to about 35 mole %, and optionally fromabout 27.5 mole % to about 32.5 mole %.

Any dihydric alcohol, glycol, or diol known in the art can be used asthe dihydric alcohol component of the aliphatic-aromatic copolyester ofthe film of the present invention. Examples include unsubstituted orsubstituted; straight chain, branched, cyclic aliphatic,aliphatic-aromatic, or aromatic diols having e.g., from 2 carbon atomsto 36 carbon atoms and poly(alkylene ether) diols with molecular weightspreferably between about 250 to about 4,000. Specific examples of theuseful diol component include ethylene glycol, 1,3-propanediol,1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol,1,12-dodecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol,4,8-bis(hydroxymethyl)-tricyclo[5.2.1.0/2.6]decane,1,4-cyclohexanedimethanol, di(ethylene glycol), tri(ethylene glycol),poly(ethylene oxide) glycols, poly(butylene ether) glycols, isosorbide,and the like and mixtures of two or more. Preferred dihydric alcoholsinclude ethylene glycol, 1,3-propanediol, 1,4-butanediol,1,6-hexanediol, and poly(ethylene oxide) glycols.

The dihydric alcohol is present in the aliphatic-aromatic copolyester inan amount of from about 30 mole % to about 60 mole %, optionally fromabout 45 mole % to about 55 mole %, and optionally from about 47.5 mole% to about 52.5 mole %.

The aliphatic-aromatic copolyester component of the films describedherein may be formed including an optional polyfunctional branchingagent, such as any material with three or more carboxylic acidfunctions, hydroxy functions or a mixture thereof. Specific examples ofuseful polyfunctional branching agent component include1,2,4-benzenetricarboxylic acid (trimellitic acid),trimethyl-1,2,4-benzenetricarboxylate, 11,2,4-benzenetricarboxylicanhydride (trimellitic anhydride), 1,3,5-benzenetricarboxylic acid,1,2,4,5-benzenetetracarboxylic acid (pyromellitic acid),1,2,4,5-benzenetetracarboxylic dianhydride (pyromellitic anhydride),3,3′,4,4′-benzophenonetetracarboxylic dianhydride,1,4,5,8-naphthalenetetracarboxylic dianhydride, citric acid,tetrahydrofuran-2,3,4,5-tetracarboxylic acid,1,3,5-cyclohexanetricarboxylic acid, pentaerythritol,2-(hydroxymethyl)-1,3-propanediol, 2,2-bis(hydroxymethyl)propionic acid,and the like and mixtures of two or more thereof. The polyfunctionalbranching agent may be included when higher resin melt viscosity isdesired for specific end uses. Excessive fractions of polyfunctionalgroups (i.e., more than two functional groups) may lead to the formationof a gel fraction or insoluble crosslinked material. The total amount ofpolyfunctional branching agent may be less than about 10% of the totalmonomer composition. Alternatively the polyfunctional branching agentmay be less than about 3%, or less than about 1%.

In one embodiment of the present invention, the total amount of acidcomononer present in the aliphatic-aromatic copolyester component of thefilms described herein is from about 40 mole % to about 60 mole %; thatis, the molar amount of aromatic dicarboxylic acid plus the molar amountof aliphatic dicarboxylic acid present in the aliphatic aromaticcopolyester is from about 40 mole % to about 60 mole %. Desirably, thetotal amount of acid comonomer present in the copolyester is from about45 mole % to about 55 mole %, and even more desirably from about 47.5mole % to about 52.5 mole %.

The total amount of acid comonomer present in the aliphatic-aromaticcopolyester component of the films described herein affects the adhesionproperties between the aliphatic-aromatic copolyester and the fillermaterial component of the film, which is described below. In order forfilms to be suitable for use in absorbent products, generally lowadhesion between the filler material and the copolyester is desired. Iftoo much acid comonomer is present in the copolyester, the adhesion tothe filler material is too high. And the filler material cannot actproperly to effectuate the creation of pores around the filler materialwhen the film is stretched. This results in the film having insufficientvapor permeability.

The aliphatic-aromatic copolyester component of the films describedherein have a weight average molecular weight and a number averagemolecular weight such that the copolyester has a suitable tensilestrength. If the molecular weight numbers are too small, the copolyesterwill be too tacky and have too low of a tensile strength. If themolecular weight numbers are too high, various processing issues, suchas a need for increased temperature to deal with increased viscosity,are encountered. Suitable weight average molecular weights for thecopolyesters are from about 90,000 to about 160,000 Daltons, desirablyfrom about 100,000 to about 130,000 Daltons, and more desirably fromabout 105,000 to about 120,000 Daltons. Suitable number averagemolecular weights for the copolyesters are from about 35,000 to about70,000 Daltons, more desirably from about 40,000 to about 60,000Daltons, and more desirably from about 42,000 to about 50,000 Daltons.

The aliphatic-aromatic copolyester films of the present inventiongenerally have a thickness suitable for use in an absorbent article,such as a diaper. Typically, the films will have a thickness of lessthan about 250 micrometers, and desirably from about 2.5 micrometers toabout 130 micrometers. A standard film useful in a diaper may have athickness of from about 10 micrometers to about 25 micrometers, forexample. In some embodiments, it may be desirable to utilize a filmhaving a thickness of about 50 micrometers.

The copolyesters described herein for use in the films of the presentinvention have a glass transition temperature such that the copolyesterhas suitable flexibility characteristics for use in a film. As usedherein, “glass transition temperature” means that temperature at which apolymer becomes hard and brittle, like glass. For the copolyestersdescribed herein, it is desirable that they have a glass transitiontemperature of less than about 0° C., and optionally less than about−10° C. With glass transition temperatures less than these values, thecopolyesters have suitable properties for use in the absorbent articlesdescribed herein.

The aliphatic-aromatic copolyester films of the present invention have asuitable water vapor transmission rate such that the film allows asubstantial amount of water vapor to pass therethrough such that theprobability of skin overhydration is reduced. The films of the presentinvention can be made substantially vapor permeable through the additionof a filler particle or material during manufacturing of the films.During manufacturing, the filler material is admixed with the polymersprior to the casting of the polymers into a film. Once casted, the filmsare stretched to create tiny pores to form in the film around the fillerparticles. These pores allow vapor transmission, but do not allow asubstantial amount of liquid to pass therethrough.

The filler particles can include any suitable inorganic or organicfiller. The filler particles are preferably small, in order to maximizevapor transmission through the voids. Generally, the filler particlesshould have a mean particle diameter of about 0.1-10.0 micrometers,optionally about 0.5-5.0 micrometers, and optionally about 1.5-3.0micrometers. Examples of organic fillers include starches, such asthermoplastic starches or pregelatinized starches, microcrystallinecellulose, and polymeric microbeads. Other Suitable fillers include,without limitation, calcium carbonate, non-swellable clays, silica,alumina, barium sulfate, sodium carbonate, talc, magnesium sulfate,titanium dioxide, zeolites, aluminum sulfate, diatomaceous earth,magnesium sulfate, magnesium carbonate, barium carbonate, kaolin, mica,carbon, calcium oxide, magnesium oxide, aluminum hydroxide and polymerparticles. Calcium carbonate is a presently preferred filler material.

The filler particles may optionally be coated with a minor quantity(e.g. up to 2% by weight) of a fatty acid or other material to easetheir dispersion in the polymer matrix prior to casting. Suitable fattyacids include without limitation stearic acid, or a larger chain fattyacid such as behenic acid. The amount of filler particles in the filmshould range from about 30% to about 80% (by weight film and fillerparticles), optionally from about 40% to about 70% (by weight of filmand filler particles), and optionally from about 50% to about 65% (byweight film and filler particles), and optionally from about 50% toabout 55% (by weight of film and filler particles).

Filler particles may be microporous or not. Microporous refers to amaterial that has pores, generally in the range of from about 2Angstroms to about 50 Angstroms, that form a continuouslyinterconnecting void space or network. The shape of the filler particlemay be generally spherical or rounded. Other embodiments includeplate-like, needle-like, or irregular shapes, points, or sharp edges.

In some embodiments of the present invention, the stretched filmsdescribed herein have a water vapor transmission rate of at least about2000 g/m²/day, optionally at least about 5000 g/m²/day, optionally atleast about 10,000 g/m²/day, and optionally 25,000 g/m²/day. At theselevels, the films allow a sufficient amount of water vapor to passthrough to protect the skin from overhydration.

In addition to a suitable water vapor transmission rate, it is alsodesirable that the stretched films described herein resist a hydrostaticpressure such that the films do not allow a substantial amount of liquidwater to pass through upon the application of pressure. Generally, it isdesirable that the films resist a hydrostatic pressure of at least about60 millibar, optionally at least about 80 millibar, optionally at leastabout 120 millibar, and optionally at least about 180 millibar withoutallowing liquid water to pass.

In addition to a suitable water vapor transmission rate and a suitableresistance to hydrostatic pressure, it is also desirable that the filmsdescribed herein have a suitable modulus of elasticity. The tensileproperties of the films disclosed herein can be determined by oneskilled in the art using the “Standard Test Method For TensileProperties of Plastics” ASTM D 938-99, published by the American Societyfor Testing and Materials, West Conshohocken, Pa. The procedureindicates that break stress is the tensile stress at the breakelongation (i.e., the elongation at which the sample breaks); yieldstress is the tensile stress at the first point on the stress-straincurve at which an increase in strain occurs without an increase stress;and modulus of elasticity is the ratio of stress (nominal) tocorresponding strain below the proportional limit of a material.

Precursor films desirably have a modulus of elasticity ratio which issuitable to characterize a desirable adhesion between filler particlesand the film. As used herein, the term “modulus ratio” means the modulusof elasticity of a filled precursor film divided by the modulus ofelasticity of an unfilled film. For precursor films comprising about 50%filler material, the modulus ratio is desirably from about 0.5 to about3.5, optionally from about 0.75 to about 3.25, and optionally from about1.0 to about 3.0. For precursor films comprising about 55% fillermaterial, the modulus ratio is from about 0.45 to about 4.25, optionallyfrom about 0.75 to about 3.75, and optionally from about 1.0 to about3.5. Within these ratios, a film has the desired modulus of elasticityto provide a desired rate of adhesion between the film and the fillerparticles.

Additionally, precursor films desirably have suitable elongationcharacteristics; that is, the precursor film can be elongated asufficient amount to achieve the desired film thickness and level ofbreathability before breaking. Measurements of elongation of a filminclude % strain at break point, break stress (MPa) and yield stress(MPa). For precursor films comprising about 50% filler material, it isdesirable that the film can be stretched in the machine direction andhave from about 50% strain to about 1000% strain, optionally from about300% strain to about 1000% strain, and optionally from about 450% strainto about 1000% strain before breaking. As used herein, “strain” meansthe ratio of the length of the stretched film to the length of theprecursor film minus one, which is typically reported as a percentage.

For precursor films comprising about 55% filler material, it isdesirable that the film can be stretched in the machine direction andhave from about 50% strain to about 1000% strain, optionally from about75% strain to about 1000% strain, and optionally from about 250% strainto about 1000% strain before breaking.

It is also beneficial for the precursor films to have a suitable drawratio in the machine direction. As used herein, “draw ratio” means thelength of stretched film divided by the length of unstretched film. Inone embodiment, the draw ratio of the precursor films described hereinis at least about 2.5 to about 10, optionally from about 3.5 to about10, and optionally from about 4.5 to about 10.

For precursor films comprising about 50% filler material, it isdesirable that the film can be stretched in the cross direction and notbreak until from about 50% strain to about 1000% strain, optionally fromabout 300% strain to about 1000% strain, and optionally from about 450%strain to about 1000% strain before breaking. For precursor filmscomprising about 55% filler material, it is desirable that the film canbe stretched in the cross direction and not break until from about 50%strain to about 1000% strain, optionally from about 250 strain to about1000% strain, and optionally from about 350% strain to about 1000%strain before breaking.

For precursor films comprising about 50-55% filler material, it isdesirable that the film can be stretched in the machine direction andhave a break stress of from about 4 to about 30 MPa, optionally fromabout 6 to about 20 MPa, and optionally from about 8 to about 15 MPa.For precursor films comprising from about 50 to about 55% fillermaterial, it is also desirable that the film can be stretched in themachine direction and have a yield stress of from about 4 to about 16MPa, optionally from about 6 to about 14 MPa, and optionally from about8 to about 10 MPa. As one skilled in the art will understand based onthe disclosure herein, the films described herein can be stretched byany method known in the art. For example, the films can be stretched byblowing, using tenter hooks, or by using differential speeds on rollers.

For stretched films, it is preferred that the film have a modulus ofelasticity of from about 50 to about 250 MPa, optionally from about 70to about 150 MPa, and optionally from about 80 to about 100 MPa.Regarding elongation, it is preferred that stretched films be capable ofbeing elongated in the machine direction from about 15 to about 100%strain, optionally from about 20 to about 60% strain, and optionallyfrom about 30 to about 50% strain before breaking. Stretched films arealso desirably capable of being stretched in the cross direction fromabout 150 to about 500% strain, optionally from about 175 to about 400%strain, and optionally from about 200 to about 300% strain beforebreaking. Also, when being stretched in the machine direction, stretchedfilms desirably have a break stress of from about 10 to about 50 MPa,optionally from about 15 to about 40 MPa, and optionally from about 25to about 35 MPa.

As noted above, the aliphatic aromatic copolyesters described herein canbe prepared from the aliphatic dicarboxylic acid, aromatic dicarboxylicacid, and dihydric acid monomers using any conventional process known tothose skilled in the art. For example, the copolyesters may be preparedusing a conventional polycondensation technique, or a conventional meltpolymerization method. Additionally, aliphatic-aromatic copolyesters maybe obtained commercially from BASF (Mount Olive, N.J.), IRe Chemical(Seoul, Korea) and Eastman Chemical (Kingsport, Tenn.).

Films comprising the copolyesters and filler particles described hereinand suitable for use in the absorbent articles described herein may beprepared utilizing any conventional film forming technique includingextrusion casting and melt blowing. An extrusion casting technique maybe used in combination with film annealing, film stretching, and/or heatsetting after stretch operations.

In one embodiment, during the film casting operation, cast rolls areoptionally set at the temperature at the roll surface of from about 20°C. to about 70° C., optionally from about 30° C. to about 60° C. andoptionally from about 45° C. to about 55° C. After the film is cast on acast roll, the film may be cooled and annealed at temperatures rangingfrom about 40° C. to about 60° C. This cooling and annealing occurs asthe film is conveyed (on a series of rollers, on a conveyer belt, on anair conveyer etc.) under low tension. In this context, “low tension”indicates that the film stretches less than 100%, optionally less than25%, or less than 10% as it is conveyed. This section of the film-makingapparatus extending from the cast roll to the stretching operation isreferred to as the casting line.

The casting line length is from about 5 meters to about 50 meters,optionally from about 10 meters to about 30 meters. Longer line lengthmay provide longer residence time for film setting and annealing beforefilm enters stretching operation. Longer residence time will improvefilm tensile properties such as strength, drawability, and otherproperties useful for stretching operations.

In a stretching operation, film is preferably stretched at temperaturesfrom about 15° C. to about 50° C., optionally from about 25° C. to about40° C., and optionally from about 30° C. to about 40° C. Cold stretchingcould improve void formation around filler particles, but may limit filmstretchability. Optionally, film is stretched in two zones with optionalheating to a range of from about 30° C. to about 50° C. betweenstretching zones. Either a single stretch or zone or multiple zones maybe used. Films can be stretched uniaxially, biaxially or both uniaxiallyand biaxially (at different times). Uniaxial stretching may be in themachine direction, the cross direction, or on a bias.

The stretch or draw ratio during stretching operation is from about 2.5to about 10; e.g., the linear speed of the film exiting the stretchingoperation is 2.5 to 10 times the speed of the precursor film enteringthe stretching operation. Optionally, the stretch or draw ratio is fromabout 3.5 to about 7.

After stretching, the film is optionally heat-set to stabilize thestretched film. Heat-setting can be accomplished at temperatures of fromabout 40° C. to about 80° C., and optionally from about 50° C. to about70° C. The heat-setting operation could reduce shrinkage of thestretched film and improve film properties and breathability. Any knownin the art techniques for heat setting could be used including heatedrolls and oven setting. Additional treatments may be applied to improvestretched film properties such as surface treatments, UV treatments,ultrasonic treatments, and plasma treatments.

EXAMPLE 1

In this Example, aliphatic-aromatic copolyester films were preparedusing two commercially available aliphatic-aromatic copolyester resinsas starting materials. One group of films was prepared without anyfiller material, and a second group of films was prepared using acalcium carbonate filler materials at various levels (weight % of fillerbased on total weight of film and filler). One group of filled andunfilled films was prepared using Ecoflex F BX 7011 aliphatic-aromaticcopolyester (BASF), and one group of films was prepared using EnPolG8060M (IRe Chemical) aliphatic-aromatic copolyester.

Before extrusion of the films from the aliphatic-aromatic copolyesters,the one group of Ecoflex copolyesters and one group of EnPolcopolyesters were separately blended with Omya (Proctor, Vt.) 2sst 2micron calcium carbonate filler material using a Werner & Pfleiderer(Ramsey, N.J.) ZSK-30 twin screw compounding extruder. Blends of thecalcium carbonate filler material and each resin (in molten form) weremade at levels of filler equal to 40 weight % (based on the total weightof the film and the filler), 50 wt %, 55 wt %, 60 wt %, and 65 wt %.

After the resins were blended with the filler material, films of eachblend were extruded. The films were extruded using a HAAKE (ThermoElectron Corporation, Woburn, Mass.) Rheocord 90 benchtop twin screwextruder having an eight inch die. The extruder had three temperaturezones, a melt pump with controlled temperature, and a die with acontrolled temperature. Unfilled films comprising each copolyester werealso extruded.

The temperature profile used for casting the Ecoflex copolyester into afilm was as follows: 160° C., 170° C., 170° C. (extruder temperatures),170° C. (melt pump temperature), and 160° C. (die temperature). Thetemperature profile used for casting the EnPol copolyester into a filmwas as follows: 170° C., 180° C., 180° C. (extruder temperatures), 180°C. (melt pump temperature), and 180° C. (die temperature). Thetemperature profiles were selected to achieve the proper viscosity forhandling of the molten polymer. Both filled and unfilled films having athickness ranging from about 15 micrometers to about 50 micrometers wereextruded.

EXAMPLE 2

In this Example, tensile strength testing was performed on variousaliphatic-aromatic copolyester precursor films prepared in Example 1.Each film to be tested was cut into a 3 millimeter wide by 50 millimeterlong film strip for testing. The tensile testing was done pursuant toADTM D-638 using a dog bone configuration, 0.7 inch (18 millimeter)gauge length, and a cross head speed of 5 inches (127 millimeters) perminute. The films were stretched under these conditions until theybroke.

The following Exoflex-based and EnPol-based films were stretched andtested in the machine direction and in the cross direction: (1) 0%calcium carbonate at 25 micrometers; (2) 40% calcium carbonate at 50micrometers; (3) 50% calcium carbonate at 50 micrometers; (4) 55%calcium carbonate at 50 micrometers; (5) 60% calcium carbonate at 50micrometers. Also, linear low density polyethylene was tested forcomparison purposes. The results are set forth in Tables 1-5. TABLE 1Tensile Strength Properties Of Linear Low Density Polyethylene FilmsLLPDE Machine Cross Machine Direction Direction Thickness 25 25(micrometers) % Strain @ Break 700 747 Peak Stress (MPa) 31 31 Stress @Yield 8 9 (MPa) Modulus (MPa) 102 105

TABLE 2 Machine Direction Tensile Properties of Copolyester PrecursorFilms Ecoflex/ Ecoflex/ Ecoflex/ Ecoflex CaCO₃ CaCO₃ CaCO₃ Ecoflex/CaCO₃No Fill 60/40 50/50 45/55 40/60 MD MD MD MD MD Thickness 25 50 50 50 50(micrometers) % Strain @ 609 561 470 259 48 Break Peak Stress 36 18 11 912 (MPa) Stress @ Yield 8 8 9 9 12 (MPa) Modulus (MPa) 60 153 177 192277

TABLE 3 Cross Machine Direction Tensile Properties of Precursor FilmsEcoflex/ Ecoflex/ Ecoflex/ Ecoflex CaCO₃ CaCO₃ Ecoflex/CaCO₃ CaCO₃ NoFill 60/40 50/50 45/55 40/60 CD CD CD CD CD Thickness 25 50 50 50 50(micrometers) % Strain @ 945 696 484 374 45 Break Peak Stress 40 16 10 810 (MPa) Stress @ Yield 9 8 9 8 10 (MPa) Modulus (MPa) 72 155 183 219233

TABLE 4 Machine Direction Tensile Properties of Copolyester PrecursorFilms EnPol/ EnPol/ EnPol/ EnPol/ EnPol CaCO₃ CaCO₃ CaCO₃ CaCO₃ No Fill60/40 55/45 50/50 45/55 MD MD MD MD MD Thickness 25 50 50 50 50(micrometers) % Strain @ Break 715 378 330 231 8 Peak Stress 32 17 13 1214 (MPa) Stress @ yield 7 11 13 12 14 (MPa) Modulus (MPa) 78 210 237 227352

TABLE 5 Cross Machine Direction Tensile Properties of Precursor FilmsEnPol/ EnPol/ EnPol/ EnPol/ EnPol CaCO₃ CaCO₃ CaCO₃ CaCO₃ No Fill 60/4050/50 45/55 40/60 CD CD CD CD CD Thickness 25 50 50 50 50 (micrometers)% Strain @ Break 889 474 203 136 7 Peak Stress 36 14 12 11 12 (MPa)Stress @ Yield 14 11 12 11 12 (MPa) Modulus (MPa) 86 210 237 262 332

FIGS. 1 and 2 are derived from the data in Tables 2-5. FIG. 1 plots thegeometric mean of the MD and CD strain at break data against the calciumcarbonate filler level. FIG. 2 plots the geometric mean of the MD and CDmodulus data against the calcium carbonate filler level. Geometric meanis calculated by taking the square root of the product of the machinedirection data times the cross machine direction data.

The data in Tables 2-5 and in FIGS. 1 and 2 show that the strain atbreak for unfilled (i.e., 0% calcium carbonate) Exoflex and EnPol arequite close. Also the unfilled films have similar modulus. But as thefiller level increases, the values for the Ecoflex and EnPol filmsdiverge. Considering the films containing 40% or more filler, theEnPol-based films are stiffer than the Ecoflex-based films as shown bythe higher modulus and lower strain at break for the EnPol-based filmsrelative to the Ecoflex-based films. These differences indicate that thefiller particles adhere to the EnPol-based films more strongly than thefiller particles adhere to the Ecoflex-based films.

It is desirable that the filler particles do not adhere too strongly tothe copolyesters. Weaker adhesion permits more stretching of the filmwithout breakage. Also, weaker adhesion results in more debonding(separation) of the filler particles from the polymer when the film isstretched. Such separation provides voids in the film, which enhancesvapor permeability. These voids also tend to result in a lower densityfilm.

EXAMPLE 3

In this Example, various Ecoflex-based and EnPol-based precursor filmsextruded in Example 1 were stretched to produce stretched films tocreate pores around the calcium carbonate filler material such that thefilms could be further evaluated for hydrohead pressure, water vaportransmission rate, and tensile strength. The films were stretched tocreate the pores prior to further analysis in order to test the films asthey would be used in a commercial embodiment; that is, the filled filmsextruded in Example 1 would first be stretched according to theprocedure in this Example prior to being used in an absorbent article asthis stretching creates the pores in the film that allow for vaportransmission.

Each film was cut into sheets measuring about 18.0 centimeters wide byabout 10.0 centimeters long. Each film was then stretched to about 470%(strain) of its original length at a rate of 840 millimeters/minute,which resulted in a stretch of 2200%/minute and a draw of 350%. AllEcoflex films were successfully stretched up to a concentration of 60%calcium carbonate. The EnPol films could not be successfully stretchedto the same extent with more than a concentration of 40% calciumcarbonate because the film broke at higher calcium carbonate loadinglevels. It is hypothesized that excessive adhesion of the copolyester tothe filler particles resulted in the EnPol film's lesser tolerance forstretching than the Ecoflex films.

To account for the adhesion differences between the two films,analytical work (gel permeation chromatography for molecular weightdetermination) was performed on the Ecoflex and EnPol copolyesters. Itwas determined that the EnPol resins had a higher weight averagemolecular weight (119,300 Daltons) as compared to the Ecoflex resins(109,850 Daltons). The EnPol resin also had a lower number averagemolecular weight (43,800 Daltons) as compared to the Ecoflex resin(46,700 Daltons). It was also determined that the EnPol resin had ahigher total amount of acid monomer content (57 mole %) as compared toEcoflex (51 mole %). It appears that the combination of molecular weightdifferences and difference in total acid monomer content caused theEnPol films to have an increased amount of tackiness which does notallow for as much debonding as compared to the Ecoflex films.

EXAMPLE 4

In this Example, the resistance to hydrostatic pressure of various filmsstretched according to Example 3 were evaluated. The resistance of amaterial to liquid penetration is measured by hydrostatic pressure. Theresistance to hydrostatic pressure of various films were determinedusing ASTM Standard Test Method for Coated Fabrics, designation D751,“Hydrostatic Resistance Procedure A-Mullen Type Tester” with theexception that in paragraph 40.1.1, the dial reading is taken when thethird drop of water is observed, rather than when the first drop isobserved. All films were stretched in the machine direction.

The following Ecoflex comprising films, stretched according to Example3, were evaluated: Exoflex with 55% calcium carbonate (25 micrometers);Exoflex with 50% calcium carbonate (25 micrometers); and Ecoflex with40% calcium carbonate (20 micrometers). The following EnPol comprisingfilm, also stretched according to Example 3, was evaluated: EnPol with40% calcium carbonate (23 micrometers). The results of the hydrostaticpressure analysis are shown in Table 6. TABLE 6 Hydrohead PressureThickness Stretch Pressure at Base Resin % CaCO₃ (micrometers) DirectionFailure (Mbar) Ecoflex 55 25 MD 100 Ecoflex 50 25 MD 100 Ecoflex 40 20MD 148 EnPol 40 23 MD 104

As the data in Table 6 indicate, all of the films tested had highhydrohead pressure resistance values, which indicates that all of thefilms would be resistant to allowing water droplets to pass therethroughduring use. Notably, the Ecoflex comprising 40% calcium carbonate (20micrometers) had a value of 148.00, which indicates that it would behighly resistant to the passage of liquid therethrough.

EXAMPLE 5

In this Example, the water vapor transmission rates of various filmsstretched according to Example 3 were evaluated. Water vaportransmission rate measures the ability of water vapor to penetratethrough a film. The water vapor transmission rate of various films weredetermined using ASTM F-1249 using a Permatran 100 K analyzer availablefrom MOCON (Minneapolis, Minn.). Films were either stretched in themachine direction or the cross direction as noted below.

The following Ecoflex comprising films were evaluated: Exoflex with 55%calcium carbonate (19 micrometers machine direction); Exoflex with 55%calcium carbonate (25 micrometers machine direction); Ecoflex with 55%calcium carbonate (25 micrometers cross direction); Ecoflex with 50%calcium carbonate (23 micrometers machine direction); Ecoflex with 50%calcium carbonate (19 micrometers machine direction); Ecoflex with 40%calcium carbonate (17 micrometers machine direction); and Ecoflex with40% calcium carbonate (22 micrometers machine direction). The followingEnPol comprising films were evaluated: EnPol with 40% calcium carbonate(18 micrometers machine direction); EnPol with 40% calcium carbonate (20micrometers cross direction); EnPol with 40% calcium carbonate (15micrometers cross direction); EnPol with 40% calcium carbonate (25micrometers machine direction; and EnPol with 40% calcium carbonate (20micrometers machine direction). The results of the water vaportransmission rate analysis are shown in Table 7.

All Ecoflex films were prepared from resins having a temperature as theycame out of the die during casting of about 175° C. The EnPol tested at40% calcium carbonate were cast at about 160° C. TABLE 7 Water VaporTransmission Rate Thickness Stretch Base Resin % CaCO₃ (micrometers)Direction g/m²/day Ecoflex 55 19 MD 21,207 Ecoflex 55 25 MD 19,763Ecoflex 55 25 CD 16,405 Ecoflex 50 23 MD 15.660 Ecoflex 50 19 MD 13,995Ecoflex 40 17 MD 3498 Ecoflex 40 22 MD 3091 EnPol 40 18 MD 3371 EnPol 4020 CD 2918 EnPol 40 15 CD 2593 EnPol 40 23 MD 2348 EnPol 40 20 MD 2322

The data in Table 7 demonstrate that films with higher filler loadinglevels tend to have greater water vapor transmission rates than filmswith lower filler loading.

EXAMPLE 6

In this Example, the tensile strengths of various stretched filmsprepared according to Example 3, were evaluated for modulus, % strain atbreak, peak stress, and peak load using the same testing procedure asset forth in Example 2. The films were stretched in the machinedirection (Table 8) and in the cross machine direction (Table 9). Theresults are set forth in Tables 8 and 9. TABLE 8 Tensile Properties ofStretched Breathable Films; Films MD Stretched and MD Tested EnPol/CaCO₃Ecoflex CaCO₃ 60/40 MD 45/55 MD LLPDE Stretched Stretched MD MD MDThickness 23 23 25 (micrometers) % Strain @ break 72 47 35 Peak Stress34 41 33 (MPa) Peak Load (gf) 234 287 253 Modulus (MPa) 322 125 85

TABLE 9 Tensile Properties of Stretched Breathable Films; Films MDStretched and CD Tested EnPol/CaCO₃ Ecoflex CaCO₃ 60/40 MD 45/55 MDLLPDE Stretched Stretched CD CD CD Thickness 23 23 25 (micrometers) %Strain @ break 187 460 222 Peak Stress 3 4 2 (MPa) Peak Load (gf) 21 2814 Modulus (MPa) 73 88 12

As the data in these Tables indicate, both the EnPol and Ecoflex-basedfilms have similar properties to LLPDE once stretched.

It will be appreciated that details of the foregoing embodiments, givenfor purposes of illustration, are not to be construed as limiting thescope of this invention. Although only a few exemplary embodiments ofthis invention have been described in detail above, those skilled in theart will readily appreciate that many modifications are possible in theexemplary embodiments without materially departing from the novelteachings and advantages of this invention. Accordingly, all suchmodifications are intended to be included within the scope of thisinvention, which is defined in the following claims and all equivalentsthereto. Further, it is recognized that many embodiments may beconceived that do not achieve all of the advantages of some embodiments,particularly of the preferred embodiments, yet the absence of aparticular advantage shall not be construed to necessarily mean thatsuch an embodiment is outside the scope of the present invention.

1. An absorbent article comprising a laminated outer cover, thelaminated outer cover comprising a biodegradable stretchedaliphatic-aromatic copolyester film, the film comprising fillerparticles and a copolyester comprising from about 10 mole % to about 30mole % of aromatic dicarboxylic acid or ester thereof, from about 20mole % to about 40 mole % of aliphatic dicarboxylic acid or esterthereof, from about 30 mole % to about 60 mole % dihydric alcohol, andwherein the weight average molecular weight of the copolyester is fromabout 90,000 to about 160,000 Daltons, and wherein the number averagemolecular weight of the copolyester is from about 35,000 to about 70,000Daltons, and wherein the glass transition temperature of the copolyesteris less than about 0° C.
 2. The absorbent article as set forth in claim1 wherein the filler particles are present in the film in an amount offrom about 30% (by weight of film and filler particles) to about 80% (byweight of film and filler particles).
 3. The absorbent article as setforth in claim 1 wherein the filler particles are present in the film inan amount of from about 50% (by weight of film and filler particles) toabout 55% (by weight of film and filler particles).
 4. The absorbentarticle as set forth in claim 1 wherein the filler particles areselected from the group consisting of calcium carbonate, non-swellableclays, silica, alumina, barium sulfate, sodium carbonate, talc,magnesium sulfate, titanium dioxide, zeolites, aluminum sulfate,diatomaceous earth, magnesium sulfate, magnesium carbonate, bariumcarbonate, kaolin, mica, carbon, calcium oxide, magnesium oxide,aluminum hydroxide and polymer particles.
 5. The absorbent article asset forth in claim 4 wherein the filler particles are calcium carbonate.6. The absorbent article as set forth in claim 1 wherein the fillerparticles are nonporous.
 7. The absorbent article as set forth in claim1 wherein the copolyester comprises from about 15 mole % to about 25mole % of aromatic dicarboxylic acid or ester thereof, from about 25mole % to about 35% percent of aliphatic dicarboxylic acid or esterthereof, and from about 45 mole % to about 55 mole % dihydric alcoholand wherein the weight average molecular weight of the copolyester isfrom about 100,000 to about 130,000 Daltons, and wherein the numberaverage molecular weight of the copolyester is from about 40,000 toabout 60,000 Daltons.
 8. The absorbent article as set forth in claim 1wherein the copolyester comprises from about 17.5 mole % to about 22.5mole % of aromatic dicarboxylic acid or ester thereof, from about 27.5mole % to about 32.5 mole % percent of aliphatic dicarboxylic acid orester thereof, and from about 47.5 mole % to about 52.5 mole % dihydricalcohol and wherein the weight average molecular weight of thecopolyester is from about 105,000 to about 120,000 Daltons, and whereinthe number average molecular weight of the copolyester is from about42,000 to about 50,000 Daltons.
 9. The absorbent article as set forth inclaim 1 wherein the aromatic dicarboxylic acid or ester thereof isselected from the group consisting of unsubstituted and substitutedaromatic dicarboxylic acids and C₁-C₆ esters of aromatic dicarboxylicacids.
 10. The absorbent article as set forth in claim 1 wherein thearomatic dicarboxylic acid or ester thereof is selected from the groupconsisting of terephthalic acid, dimethyl terephthalate, isophthalicacid, dimethyl isophthalate, 2,6-napthalene dicarboxylic acid,dimethyl-2,6-naphthalate, 2,7-naphthalenedicarboxylic acid,dimethyl-2,7-naphthalate, 3,4′-diphenyl ether dicarboxylic acid,dimethyl-3,4′diphenyl ether dicarboxylate, 4,4′-diphenyl etherdicarboxylic acid, dimethyl-4,4′-diphenyl ether dicarboxylate,3,4′-diphenyl sulfide dicarboxylic acid, dimethyl-3,4′-diphenyl sulfidedicarboxylate, 4,4′-diphenyl sulfide dicarboxylic acid,dimethyl-4,4′-diphenyl sulfide dicarboxylate, 3,4′-diphenyl sulfonedicarboxylic acid, dimethyl-3,4′-diphenyl sulfone dicarboxylate,4,4′-diphenyl sulfone dicarboxylic acid, dimethyl-4,4′-diphenyl sulfonedicarboxylate, 3,4′-benzophenonedicarboxylic acid,dimethyl-3,4′-benzophenonedicarboxylate, 4,4′-benzophenonedicarboxylicacid, dimethyl-4,4′-benzophenonedicarboxylate, 1,4-naphthalenedicarboxylic acid, dimethyl-1,4-naphthalate, 4,4′-methylene bis(benzoicacid), dimethyl-4,4′-methylenebis(benzoate), and mixtures of two or morethereof.
 11. The absorbent article as set forth in claim 1 wherein thealiphatic dicarboxylic acid or ester thereof is selected from the groupconsisting of oxalic acid, dimethyl oxalate, malonic acid, dimethylmalonate, succinic acid, dimethyl succinate, methylsuccinc acid,glutaric acid, dimethyl glutarate, 2-methylglutaric acid,3-methylglutaric acid, adipic acid, dimethyl adipate, 3-methyladipicacid, 2,2,5,5-tetramethylhexanedioic acid, pimelic acid, suberic acid,azelaic acid, dimethyl azelate, sebacic acid, 1,11-undecanedicarboxylicacid, 1,10-decanedicarboxylic acid, undecanedioic acid,1,12-dodecanedicarboxylic acid, hexadecanedioic acid, docosanedioicacid, tetracosanedioic acid, dimer acid, 1,4-cyclohexanedicarboxylicacid, dimethyl-1,4-cyclohexanedicarboxylate, 1,3-cyclohexanedicarboxylicacid, dimethyl-1,3-cyclohexanedicarboxylate, 1,1-cyclohexanediaceticacid, and mixtures of two or more thereof.
 12. The absorbent article asset forth in claim 1 wherein the aliphatic dicarboxylic acid or esterthereof is selected from the group consisting of succinic acid, dimethylsuccinate, glutaric acid, dimethyl glutarate, adipic acid, dimethyladipate, and dimer acid.
 13. The absorbent article as set forth in claim1 wherein the dihydric alcohol is selected from the group consisting ofunsubstituted or substituted, straight chain, branched, or cyclicaliphatic, aliphatic-aromatic, or aromatic diols having from 2 carbonatoms to 36 carbon atoms and poly(alkylene ether) glycols with molecularweights from about 250 to about 4,000.
 14. The absorbent article as setforth in claim 1 wherein the dihydric alcohol is selected from the groupconsisting of ethylene glycol, 1,3-propanediol, 1,4-butanediol,1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol,1,14-tetradecanediol, 1,16-hexadecanediol,4,8-bis(hydroxymethyl)-tricyclo[5.2.1.0/2.6]decane,1,4-cyclohexanedimethanol, di(ethylene glycol), tri(ethylene glycol),poly(ethylene oxide) glycols, poly(butylene ether) glycols, isosorbide,and mixtures of two or more thereof.
 15. The absorbent article as setforth in claim 1 wherein the dihydric alcohol is selected from the groupconsisting of ethylene glycol, 1,3-propanediol, 1,4-butanediol,1,6-hexanediol, and poly(ethylene oxide) glycols.
 16. The absorbentarticle as set forth in claim 1 wherein the film additionally comprisesa polyfunctional branching agent.
 17. The absorbent article as set forthin claim 16 wherein the polyfunctional branching agent is selected fromthe group consisting of a material with three or more carboxylic acidfunctions, three or more hydroxy functions, and mixtures thereof. 18.The absorbent article as set forth in claim 16 wherein thepolyfunctional branching agent is selected from the group consisting of1,2,4-benzenetricarboxylic acid (trimellitic acid),trimethyl-1,2,4-benzenetricarboxylate, 1,2,4-benzenetricarboxylicanhydride (trimellitic anhydride), 1,3,5-benzenetricarboxylic acid,1,2,4,5-benzenetetracarboxylic acid (pyromellitic acid),1,2,4,5-benzenetetracarboxylic dianhydride (pyromellitic anhydride),3,3′,4,4′-benzophenonetetracarboxylic dianhydride,1,4,5,8-naphthalenetetracarboxylic dianhydride, citric acid,tetrahydrofuran-2,3,4,5-tetracarboxylic acid,1,3,5-cyclohexanetricarboxylic acid, pentaerythritol,2-(hydroxymethyl)-1,3-propanediol, 2,2-bis(hydroxymethyl)propionic acid,and mixtures of two or more thereof.
 19. The absorbent article as setforth in claim 1 wherein the aromatic dicarboxylic acid is terephthalicacid, the aliphatic dicarboxylic acid is adipic acid, and the dihydricalcohol is 1,4 butanediol.
 20. The absorbent article as set forth inclaim 19 wherein the filler material is calcium carbonate.
 21. Theabsorbent article as set forth in claim 1 wherein the film has athickness of less than about 250 micrometers.
 22. The absorbent articleas set forth in claim 1 wherein the film has a thickness of from about2.5 micrometers to about 130 micrometers.
 23. The absorbent article asset forth in claim 1 wherein the laminated outercover further comprisesa nonwoven material.
 24. The absorbent article as set forth in claim 23wherein the nonwoven material is a spunbonded nonwoven material.
 25. Theabsorbent article as set forth in claim 23 wherein the nonwoven materialhas a basis weight of less than about 30 grams per square meter.
 26. Theabsorbent article as set forth in claim 23 wherein the film and thenonwoven material are bonded together with an adhesive.
 27. Theabsorbent article as set forth in claim 23 wherein the film and thenonwoven material are thermally bonded together.
 28. The absorbentarticle as set forth in claim 23 wherein the film and the nonwovenmaterial are ultrasonically bonded together.
 29. The absorbent articleas set forth in claim 1 wherein the laminated outercover furthercomprises a bonded carded web.
 30. The absorbent article as set forth inclaim 1 wherein the laminated outercover further comprises aspunbond-meltblown laminate.
 31. The absorbent article as set forth inclaim 1 wherein the laminated outercover further comprises a spunlacenonwoven.
 32. The absorbent article as set forth in claim 1 wherein thelaminated outercover further comprises a polylactic acid-basedsubstrate.
 33. The absorbent article as set forth in claim 1 wherein thefilm has a hydrostatic pressure resistance of at least about 60millibar.
 34. The absorbent article as set forth in claim 1 wherein thefilm has a hydrostatic pressure resistance of at least about 80millibar.
 35. The absorbent article as set forth in claim 1 wherein thefilm has a hydrostatic pressure resistance of at least about 120millibar.
 36. The absorbent article as set forth in claim 1 wherein thefilm has a hydrostatic pressure resistance of at least about 180millibar.
 37. The absorbent article as set forth in claim 1 wherein thefilm has a water vapor transmission rate of at least about 2000g/m²/day.
 38. The absorbent article as set forth in claim 1 wherein thefilm has a water vapor transmission rate of at least about 5,000g/m²/day.
 39. The absorbent article as set forth in claim 1 wherein thefilm has a water vapor transmission rate of at least about 10,000g/m²/day.
 40. The absorbent article as set forth in claim 1 wherein thefilm has a water vapor transmission rate of at least about 25,000g/m²/day.
 41. The absorbent article as set forth in claim 1 wherein thefilm has a modulus of elasticity of from about 50 MPa to about 250 MPa.42. The absorbent article as set forth in claim 1 wherein the film has amodulus of elasticity of from about 70 MPa to about 150 MPa.
 43. Theabsorbent article as set forth in claim 1 wherein the film has a modulusof elasticity of from about 80 MPa to about 100 MPa.
 44. The absorbentarticle as set forth in claim 1 wherein the film can be stretched in themachine direction and not break until from about 15% strain to about100% strain is reached.
 45. The absorbent article as set forth in claim1 wherein the film can be stretched in the machine direction and notbreak until from about 20% strain to about 60% strain is reached. 46.The absorbent article as set forth in claim 1 wherein the film can bestretched in the machine direction and not break until from about 30%strain to about 50% strain is reached.
 47. The absorbent article as setforth in claim 1 wherein the film can be stretched in the crossdirection and not break until from about 150% strain to about 500%strain is reached.
 48. The absorbent article as set forth in claim 1wherein the film can be stretched in the cross direction and not breakuntil from about 175% strain to about 400% strain is reached.
 49. Theabsorbent article as set forth in claim 1 wherein the film can bestretched in the cross direction and not break until from about 200%strain to about 300% strain is reached.
 50. The absorbent article as setforth in claim 1 wherein the film has a break stress of from about 10MPa to about 50 MPa.
 51. The absorbent article as set forth in claim 1wherein the film has a break stress of from about 15 MPa to about 40MPa.
 52. The absorbent article as set forth in claim 1 wherein the filmhas a break stress of from about 25 MPa to about 35 MPa.
 53. Theabsorbent article as set forth in claim 1 wherein the absorbent articleis selected from the group consisting of diapers, training pants, andadult incontinence garments.
 54. An absorbent article comprising alaminated outer cover, the laminated outer cover comprising abiodegradable stretched aliphatic-aromatic copolyester film, the filmcomprising filler particles and a copolyester comprising from about 10mole % to about 30 mole % terephthalic acid, from about 20 mole % toabout 40 mole % adipic acid, from about 30 mole % to about 60 mole %1,4-butanediol, and wherein the copolyester has a weight averagemolecular weight of from about 90,000 to about 160,000 Daltons and anumber average molecular weight of from about 35,000 to about 70,000Daltons, and wherein the glass transition temperature of the copolyesteris less that about 0° C.
 55. The absorbent article as set forth in claim54 wherein the filler particles are present in the film in an amount offrom about 30% (by weight of film and filler particles) to about 80% (byweight of film and filler particles).
 56. The absorbent article as setforth in claim 54 wherein the filler particles are selected from thegroup consisting of calcium carbonate, non-swellable clays, silica,alumina, barium sulfate, sodium carbonate, talc, magnesium sulfate,titanium dioxide, zeolites, aluminum sulfate, diatomaceous earth,magnesium sulfate, magnesium carbonate, barium carbonate, kaolin, mica,carbon, calcium oxide, magnesium oxide, aluminum hydroxide and polymerparticles.
 57. The absorbent article as set forth in claim 56 whereinthe filler particles are calcium carbonate.